Method for preparing a cement base material, together with a cement composition containing this base material

Abstract

The invention relates to a method for preparing a hydraulically settable cement base material starting from steel slags formed in a steel-making process, which method comprises the formation, in steel slags in the liquid state, of a ferrite gradient by adding a ferrite-precipitating compound, the separation, if required, of the high-ferrite fraction formed, the separation of at least the low-ferrite fraction formed, the cooling and the comminution thereof to obtain a hydraulically settable material. The ferrite-precipitating compound used has preferably acid components, and can expediently generate silicic acid. At least before the cooling of the low-ferrite fraction, the aluminum content of the liquid slag material is regulated by the addition of an aluminate-containing material, such as bauxite. The high-ferrite fraction separated can be returned to the steel-making process to reduce or remove the addition of a flux in the production of steel.

What is claimed is: 
     
       1. A method for preparing a hydraulically settable cement base material and a flux for steel making starting from steel slags formed in a steel-making process, which method comprises the steps of adding an aluminate-containing material to the liquid slag material in the steel making vessel, separating the thus obtained slag material, forming a ferrite gradient in the obtained slags in the liquid state, in the absence of liquid steel, by adding a ferrite-precipitating compound, to obtain a high-ferrite fraction and a low-ferrite fraction, separating the low-ferrite fraction from the high ferrite fraction, cooling and comminuting the low ferrite fraction to obtain said hydraulically settable cement base material, and adding a flux to the steel making process by returning the high-ferrite fraction thereto. 
     
     
       2. A method according to claim 1, wherein the ferrite-precipitating compound used is a material having acid components. 
     
     
       3. A method according to claim 2, wherein the ferrite precipitating compound is a material generating silicic acid, selected from the group consisting of silica mineral and SiO 2 . 
     
     
       4. A method according to claim 3, wherein the silica mineral used is selected from the group consisting of sand and quartz. 
     
     
       5. A method according to claim 1, wherein the aluminate-containing material used is bauxite. 
     
     
       6. A method according to claim 1, wherein the ferrite gradient is formed by the addition of fly ash or of ground, granulated blast-furnace slag.